SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '52eddc518c358289d3c4926cac955468d86fb569fb35d2088fede2b4589d47fa' 
  AND token = 'me0/Nz+zjuHhoZF4YJvs7P98wRgIlA+a0zXLIMZywqs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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