SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c9c6928c8116e9d2ae5e592fa50eb03bda1230da126e47ae3d2be688a9263a45' 
  AND token = 'fBCo2vKV0SlZU9QACOPensIPh0FIh3ULrv/RiWPgvwE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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