SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '3700dcc7815ba429992b8dabbb0555004a34656db7508e6d788b0b597ed2ebbe' 
  AND token = 'oradnYU2zNTg6nulOKErwBDv5mPNuHDEXAMRDdrWlkI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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