SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b50b175b619c2a1a96f9255687da780a1ffb1be0f6e352ac8b881a4a25b6ca3' 
  AND token = '8f+4vqDRP3WzOVCS9vGSkbtm12H9ZXUFrs+o7hf/Wac=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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