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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'ef5e24fd91eecc0a95fd1ad2c5616c2641c8bd99d8f55268cc24b91a44222839' 
  AND token = 'a9WgEG1notfpyzn0rfAGqzCzMkBkhWPwovEn6SnHDPg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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