SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '96f8d2c3ad9a9ebd9a4875f278a7cf31371ed17cad0a2dbcd16eb18d23e05425' 
  AND token = 'VAMvtnA3Oh6Jq8VQMyFK2L/Xf0Vh3Pa4m5fjZCfnbxM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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