SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6818427213874b6fbc6cc352f323e4c2490f6036b794352c099cc9c5d2e3a073' 
  AND token = 'B+N+H4bPhQGGqCwejZlVvRxWhwMZqe4DHdpTA6UFJtM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00056

JSON explain

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