SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '396b1d5a88e0b57895302943816a2045eeb1d45818d989136af85f5645d51980' 
  AND token = 'xwYr7RhaKRP33Xtz7+8yMNrHM4qaaNuxG3FfWlMYi7o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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