SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = '87bc7a9254833df459c124fff654973b133df78291cd60f8869fb59137741a18' 
  AND token = 'wVb0qM2/52QHezxZI63wi6YOqfKaylG4eZeZOijXWPc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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