SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3515944982dcd838da824fa18caeae3873138144e1f8ef83af8fea303b66c9dd' 
  AND token = 'yEwBlgxyuNdkaO3LGlA3jTDDJoVBhWkLkKLgQmtrYao=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00036

JSON explain

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