SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fdb33dde9f5a6ace4d69dc971d07037596346a259f67e1c26158fb819a1c0350' 
  AND token = 'BCUHYnMi7jjvfzmQw0UxS0VoPnCy/Qd9D8WvhBW+I5Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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