SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '38a989dc9f37755ca2f59fbeeb68b75d48a98da7a8dab4049b9356e8169d2650' 
  AND token = 'JYM+qb8OAn5BTV+k7yqwGqKQGgjosKjdM5z2KztC7uE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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