SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '803855e099d07fec2d5b90cee3095bc50c02c81a32e02794af07715101874ab2' 
  AND token = 'j82WLCNX3HJGciSG53TzDFwaeazMq3OzsQadIxGXwJM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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