SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '8e7028357bdd718492e3d0a9276700941672d18584360196724f0635dfada790' 
  AND token = 'nu4hMQDsWM4O00Box3Vjwsq8Yf/7h+bwiKN6SJqS5ts=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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