SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '77ed21a26fe442d361b3642341493976a0ebeae1e538e1a85f66221258a2139f' 
  AND token = 'lTkCPf+bWb7qPGpWkcqJFdPkzIEPRQTequBVCYI0oQk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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