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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3c9a9f250d15feedaf94cbe64b062098b9175412fb476474d4e4bda1a0e99c3f' 
  AND token = 't1lPhArgIGPWK/WRe4vwOQHWk2YV51fPUHLnfPOfY+k=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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