SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'c698839f119f3310f55477b3d502cdec436e461303daf6d6aaf6c7fc3e1db772' 
  AND token = 't9JGsomXO6K6rexEfrczuNRoURgTJ5XTTcl4cgiSljo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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