SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2b848ddefb66b9bc2af45369c3d9885c53b0ced1be3980621a206b148e14334' 
  AND token = 'ZDbfiDADDTAanv+yRunnPWKKCVOU9ab6zWxh+U0Nxko=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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