SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1d21369e134ed024a720afc91b854e0ad84d812524cf42a6b94963196e0c4efc' 
  AND token = 'a4r6Eoya/PQ/Adp92lICUMreiBZ+9LHtREzoyUhs+lY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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