SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8af673365406977982f73624012c51d434d55843dd1013d9f23f2e09665e2042' 
  AND token = 'f22Vf4ZbGymYLDoZuNkaWojhCJtihysIUCrdOMBN9x4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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