SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b015166cf54626fcc1e973ed831d6592480b96b201410b196a18ff1bb0008528' 
  AND token = 'QLzPn9FzwVV/gznFRkcLkfMNBTYxLtYvVmbK/8CbqjY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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