SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4a6a192d14a002138a465774f40314a68708aa9ce03b3c2b824003ace99259f2' 
  AND token = 'kp8h5c+agL6CCnO1cxKYzJ8eV8VG55KnuyJcf8U/vgQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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