SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cb8b33784fbb8e7ecc3f5d5ab51c00713664db32350739928c4651b01303333a' 
  AND token = 'PenxiJdkQgXVeU43Km36XBysxEEj/cVR5xQKYedUlh0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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