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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a9ea6722f647751d2fe67faaf0a7f3422f1f3d8506ca42a427f16bd28f772068' 
  AND token = 'Dq0f0dSNd5BO8JtrUllhhT1BFP8bQ80C5ZP0nUEA5Ro=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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