SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'aeaabf6818b046089f5571722a2d6c6708aeeb714a4208715c455dab66df1dcd' 
  AND token = 'aXyOjaQDouA7DLWJ+rPofb5z/kp/GaCkl+vgdJzbySc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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