SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bbd51493cef0f6f0bce0edc33df52da35184d5736f71dd461eaf630e08c2c6d0' 
  AND token = 'ajkqyXvdGjb71lE1/rLAPH/RDNmS4g43IjEAJiFTFyw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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