SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '159ffcfbe0141f1bf314661882ee7d5a8c5c026a37b858226c9dc958295e98f0' 
  AND token = 'Qln0Tqg3ApqJxz83WbqRD/aJNcqJuyzTtaimU0vKWuM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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