SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '278dcf7b4174956ecc7670fd0a216f113bff044333b219e51b2deee5006f0bb9' 
  AND token = 'h/fBMV3ElS7+vCEJ0bgtL2aKUSiS5HOiE7VG9DXVHA8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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