SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '99528cb4bbe1b3a0cd9238aabeed238ed29a809d129d8ac64cfbbe72018cb5e5' 
  AND token = '5CLhbrZOtYFtVN8Vms7NZ5TWUG+V5kAMXwjv/xjkM3Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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