SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7e1b9e5342457931edaff40f08fdfc489fbfed0f20b4e9dcfa56426128d27810' 
  AND token = 'xBHkDEhcpDsq2YvjweTlJmn2BbcNBdV6HgXjRpe2XGg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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