SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9f08ad76498e03af22ab111b1e076947fcb793675d9ee0550bffdfa59f8e1aeb' 
  AND token = '1Vzd6w+AWXNvf3r9Tfq4YV1PNOSfu5m7CET7gN2lrzo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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