SELECT 
  1 
FROM 
  cscart_aprillock_keys 
WHERE 
  key_id = 'a2571e3fc8c595fcc1cb0eb3551fe0e76751b41d3cd3599af0774336cda4e4bf' 
  AND token = 'gkQDUS4VdyAoKmAtUpQKUDPMVixDhhmxpJF+kV0eV3w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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