SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bc740cf9165189e1c441317b2db8ee13cce4cb66464676d5525f9c6a9a5061db' 
  AND token = 's2KPOKktmb2n0k3IuJiF4PhNzDRawTpqmogru68X03U=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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