SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'bc68bc113f8017cc3bfc121cae45d0c55cdaf73304297ebe7bed02cdc610b611' 
  AND token = 'SUtFvh2RmzkyfhINnj1yQh1TXtmjivrAlnfTGRo56js=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00037

JSON explain

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