SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b86dc7ffb6ddfcd5656849ac07eeb3fb8d3a23d7efb05f3246349a15c8969866' 
  AND token = '8f0CnF3VPsalvZuFZCIh3MqPsbtqtn8K/Erg2Lj3a9M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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