SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'efd4944ffbf422d442419f26e5599d1c2b3da15f65792f0673c5142071ebc06e' 
  AND token = '6S4pwmaiwtMd+gv22LorQLVPwohf176k8jxcTGLuVLQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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