SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8e36574b07257b57e82a8aa1af5b6b614e1265b7c6dcd8a8c064b1fdd49e0ba4' 
  AND token = 'myql+IGDqQssmrET9jmBQV/9cbyGKWCbQFWAQYuyvBs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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