SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '389ec96a0d92897548ff6a79059d43ff930660916830fdf22d8fc3a1b47d03b7' 
  AND token = 'kxEnQUEkxl3GGOefbv2tdPHmD+KHTgeP/9VfYQsm/t8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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