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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '53f3963ff0a2668f4293ae0d9ec42ca8754a09a4dd4e408cb13bc9ce656c7881' 
  AND token = 'ptw/eWS911ZgEPtWP6c3QnsWQEJ9lBjrSUo1ftPwn1Y=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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