SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '234e2ba615cc5f0a405b0709b2ce6b5503596c046e107360405ed902ff201abe' 
  AND token = 'IuYzNehv4Qu3Kt/ZOFrdththRkrpVMZCS91GKF1aBDM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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