SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '73b0dd8bd61be2b5670dc9bd7ecb96582f339f6b346ba982df285f68341f91b4' 
  AND token = '/OqklzrVxyZSKn9fjZymj8HMcN5YyJCPkVSVCWx2P1o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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