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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd423a6984f475afbbca1852e24d0e89e1a588a03b77c3c4df87e48995407cf2c' 
  AND token = 'LrsHz3cdZIqLaUSIxKmzvBXShPZHy+dDFo4ZrMCp5AA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00067

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}