SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '817c636be1048fdc75fdba867ae3ad9a2c00554273b6a1a78fbdd3dfb42d55b6' 
  AND token = 'EmNHSrXetCHgjAjfNfyLyeOcfHeyVmONyBzTwLYVpMU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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