SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1a5ceccbf42b48a098110f66d83248cf6079a271e245d813e25290d813e1b33f' 
  AND token = 'EnNqvvb4cI8T8i1lM8ARF86n7qZXj01tp2pVdJZV9WQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00055

JSON explain

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