SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '551911f44f75bf843c2eb113342c428549a8d1b360bf095786813792c88cde1f' 
  AND token = 'wWLgBM1kqxxhSrSFUgKBwz6B/j/7izee4EYFZL01sdE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}