SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cbc291bf5d3003a7841a2ac6fbe82f7c0b0aa4d0a449cde5f3b8a58bee3e26e1' 
  AND token = 'h4gqtVP3PFLvN7wpnBDBq5OHUCO0PG4vdtfYGMH5iuU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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