SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'e92127ab5fd0eb879d777f9db38e6060d7cb848622f9f3d66a27692c70911d92' 
  AND token = 'UwdSyRPShJ5QKwSL8Gd9nw4Nq+OBrc8UIPfzUNhQaYM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00059

JSON explain

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