SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '76c3a12f32a275d18bcdd961a0e3872d46e2be870a78d1f81b8985bb4db76464' 
  AND token = 'WjTCPUuSJtBUnB/lKBxbfDzFbxcNzfFrX+uO8UDbUCw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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