SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '91d2b7da15e829f0fedf6f27a8f008113dc531cfc8734d2b135ecb65561de440' 
  AND token = 'W+M/Nx/RUT8FTBrzzOJeL8ft5DlKAmm+UsarXLMZgKY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00049

JSON explain

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