SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '6531ccbb5a28fd1b17051f2c47510e82feac942922af48916ece31e29805feea' 
  AND token = 'Sq6+MF4OoLXssMCYo92cXLJD83rYMjIBfQPaS2X10oM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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