SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1089f208dce78bef238af13150440081de4f1b21fec6ee3dfa2e1852fc3d5bf1' 
  AND token = 't5wSyXY2dlvMNaKYwiMdHXPrpoNIRY08n1Kbv9E7eak=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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