SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '97c6c3de3209f2b0d32053a106c9d31e14b81bfae62156479fcc724f9da2be0d' 
  AND token = 'g40/KoMpn1BRn/fuLJmsfVSqAWdwQWUvgHUCYZj7zJY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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