SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6370ee920c21678179cd963a4c965d34bfb9aa505a1a227927e8fae8347b2794' 
  AND token = 'FHunCyvQu/5yJcKcPIqYhVNxh6ydcpI/QvVED2+wIQ8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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