SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '23d5667d13f0f520de9f159a6c64ecd84d281afd3a7a46c8f3dc3c228f5ce8e5' 
  AND token = 'LseDcwkVinQiID8WA3GVDv5SMN9iqHziB1zEZwDBAs8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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