SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7af62c62e3293e0a700fcbd3030830d6304fe56df468d5de39849cfb26d51727' 
  AND token = '4bjP1RdsJWUVJctz4lkXOJ5MbrHBImEZjnMxrgHOqyw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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