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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '87977513f8f515d7c4b98bffdcec29fe96f9751dbfc74d7aaef7d1ecfa146ec5' 
  AND token = '16SuLdtEPYEiTRTDCFIXDC2hZPpgtuabCWjhp1Pdzp8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}