SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd8a158c3d7b1e32af981e2deb7cd450eb34020b480f4fc5e21c9d4e302c11562' 
  AND token = 'FvxmnSgNxJgK7qSh1Xf6MxrOvMV3yjW+bZcVzO9F3zs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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