SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4fdb4f9e9a2b6dfbcb3e757eb7dc8e58769be370a74914bd75b78ccfd3d3cf03' 
  AND token = 'U8dsgk7axlJUlxVlO13Av0QWJABC+48AuEMd34ihkwI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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