SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ae41c461df0eeed798feb698faada9d903ea04098aea88d512080ccf17c1f263' 
  AND token = 'm6Z4z/peTneIuePBnUYF25izZW8NcZrR1J5CCZkXFzQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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