SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2828b6cad826a5b1d4bdb993c7cc886cfbf5afeea314ac9f1a00f57f61b059d' 
  AND token = 'g/jB1UKxgvFbkRLlmnH+tAtNuD/HJb+0V6I5JUG23sE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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