SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b267ce2b3ffac7bb7a403163b026b77f581682906ad6540549721470a00eade0' 
  AND token = 'mMNeLKzkRGfEXknRvUTMCKTvK8UQUBWnFNducmBcnLg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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