SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9fc181cf137bbbb9a0c1dd278a40c4b3fbff34244cfbf517b7c6b4387bbb142a' 
  AND token = 'SiwXwXhUZeTa3TC6aIqeFLDdThdakgN8tvSjzzWmkuA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00054

JSON explain

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