SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '82e63e7d8a15358feb4308b23ef8f62f2c1d0259eca8446c05a64c02a374fb55' 
  AND token = 'EuLjegFL2GcCqhgqSIMIvnwykrQ+F91sSAoBptyVDr8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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