SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a11fb6eece9d3c1a450647a88b10981bc3f2bb30f37f37ad9551bbf179c2fb47' 
  AND token = 'yh/BvajZxLEqAgfag9EV+PTtvDU6aG4vmFgtGOwDv3E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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