SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5a3d78f3395c5d820f7788315fb98b2de370a3778288d744888c44e5a55a7653' 
  AND token = 'BzTBZRLewU9hmV9qp7IH7rjTB+4tRizBksDWUI7GUJ0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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