SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dfbc009e4876ec07b4c47272f83d064b459625c18e4cad5844a88653d76da46c' 
  AND token = 'SDM70FIpd61TEL2DUKtJaSChwKUAw+4GBOwZgY3hrkc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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