SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '0e0410f0a5393de3a84e37375db4ecd9fb83b8181bb9f0302be1f4b67e289018' 
  AND token = 'ZnWb+YjqsBqPFsx+RrBZvSHGTG7GxYkgfapRchsmPCI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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