SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '28d1d5341337032318937f976aedcfd0c5af71bfb5c36406cd2acf56f90e1c20' 
  AND token = 'PYp5eoo2asVcbdRYqhOehlOBcktHmt2Ixfmc7lrUzJA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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