SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a403c3827bdd1f6ed2b1a67904f40866a37864c2160d9020e50cc6571a6b76e9' 
  AND token = 'wA6zrngskYgnl2udsZQnPXWoKrxtFyW8ITGGRGTUqr8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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