SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bc9554673994e5a916de23849576ab8db8c469de13b3d3d8481c921a7e55c5f3' 
  AND token = 'AlmbKk65LiAmAhWogJH03hnA/qvCPwNIkoNQvPDrrMs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00052

JSON explain

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