SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = '6967a03a0dc96d810f794e8a41c8d69f61101aaa2a72aa5b89805702f3bd4425' 
  AND token = 'm+csa2Qd/uDtf9KW0ugtT+bEwNSQnoidtuejT71EubE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00033

JSON explain

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