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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b9a1921d8936a01b6bbe851423b16c84c3b8344aef4eb0cd4ddc6351ddba52f2' 
  AND token = 'GZamFfumiEXYK1ECgFP3uhGbPcE3mJ5UJSK0xyoHZeA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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