SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd20d60884f8e172b6024a051be8b6b5ea0b3eab878c2e8b51e88d4fe6dff9c8b' 
  AND token = '3I6ZYAnm/m1h1GX7WCwLQ+2uizWKotHyVIEQnjBWJiM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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