SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fd5cfb2a2ab8d57876ce65669264f0a528daacb4d8372cd7f9660cab73aa4cce' 
  AND token = '2lGCuhB+Pbu+Ak2qRw2HaFmE5++26o1TMUufZcnluN8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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