SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '90cb777fadafbe7a0d5f4b22e77541b72634b09843f019feb048305f12aa0653' 
  AND token = 'Kb21MVhH4SbrMBBGUHOmpByynX+oD2qf8IHhcCvGAfU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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