SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3501e3f1f02ef51fe03a9391489fde0846eb1f07668b9282c8c45a069e52e709' 
  AND token = 'zVmQd6+hB0uztw/YZDXdc+SgXyLYB/iClaYOYX9pYNA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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