SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e78f3010372998144feb03fece5599b66918da6192fb4ab9b2b7d5f403cd4f57' 
  AND token = '6Jwn/MGX/SDCCAwajD+nj5YRjIEYDehh2/hQgNHDPaM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

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