SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '66f684d10377440a59dc742a2ea0d4670abeaa0f48eb4f08263fb757e68c2984' 
  AND token = '9hbHFPizr1se20GFYiZM/DWgVzwmmWGf2RJ7aql9nWo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

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