SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'be4d518681dc1ee32bf6d79e808d6571d4ce0494b4ead6ccb8cb7f87ecac7124' 
  AND token = '9rVFzhmNgGwL/g0T/A+DfeYjQfiDWqubHUQMWBgiAZ8=' 
  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"
    }
  }
}