SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7f41cc0498ad57378ef4663e368d5b70f9ab2cebddc76f9883e3f384641f77a9' 
  AND token = 'K3HfqjXwhtqahtPiv85cOBD+Z5IRn+gWaJ6msZpiCyg=' 
  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"
    }
  }
}