SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '832598957782cdb111baaff7b720e35a101823e73e5ecadf274ec29535c0cbb2' 
  AND token = 'y2whHKhdhHkNd7+ONPXSvpLqU4k0koaiGUf6pyDQcKg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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