SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '81a896057eb9647ab3836ccde82f0e46f97adf2d6dbbcceeb7fcbd6b4902708d' 
  AND token = 'IcjbKQSGzWUXC45T9SPVAAN3Rs9GLs7fDEs1jYedj58=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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