SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '45c5aca48e98ab8171948227585475ed1a9480e5628052f6fd54350895de63ac' 
  AND token = 'R9wA9OLUZjgFWSzUoJ8pSISIEw+/+uBh7rhkeHs3glA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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