SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '671f63ee72d4e1f880da5ee98e3b68a7a565b0e82a490ebad6594041904af550' 
  AND token = 'RGCRh0fCp84dw8e37r8XHvu/HvN8fqzQSyeH8x5XxKA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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